Fluid Mosaic Model

Hydrophilic = Hydro (Water) + Philic (Loving)

-  Molecules that are not very soluble in water, such as lipids and some proteins found in biological membrane, are termed hydrophobic

Phospholipids

-  Lipids with phosphate group that are hydrophilic while hydrocarbon chains are hydrophobic

-  When phospholipid molecules come into contact with water, they tend to line up polar heads in water and hydrocarbon tails away from water

Fluid Mosaic Model

Fluid- a bilayer that allows both phospholipids and proteins to move about laterally

Mosaic- collage of proteins randomly distributed in the bilayer

Model- a hypothesis proposal supported by evidence

Additional research from the Internet about the Fluid Mosaic Model:

• Describes the plasma membrane of animal cells
• Plasma membrane that surrounds these cells has 2 layers (bilayer), of phospholipids (fats with phosphorous attached)
• Each phospholipid molecule has a head attracted to water and a tail that repels water. Both layers of the membrane have the hydrophilic heads pointing toward the outside; the hydrophobic tails form the inside of the bilayer
• Plasma membrane forms a circle around each cell so that the water-loving heads are in contact with the fluid, and the water-fearing tails are protected on the inside
• Because cells reside in a watery solution (extracellular fluid), and they contain a watery solution inside of them
• Proteins and substances (e.g. cholesterol) are embedded in the bilayer, which gives the membrane the look of a mosaic
• Why is the plasma membrane described as the fluid-mosaic model?
• Because the membrane has the consistency of vegetable oil at body temperature, the proteins and other substances are able to move across it
• Molecules that are embedded in the plasma membrane serve a purpose:

•   Cholesterol makes the membrane more stable and prevents it from solidifying when the body temperature is low (Keeps you from freezing)
•   Carbohydrate chains attach to the outer surface of the plasma membrane on each cell. The carbohydrates supply characteristics such as blood type

Link: http://www.dummies.com/how-to/content/the-fluidmosaic-model-of-the-cell-plasma-membrane.html (Thank you, this helped me understand a lot)

Fluid goes through transverse diffusion (flip-flop) or lateral diffusion (frequent)

Cell membrane (mosaic) Structure and Composition

1. Proteins
• Interspersed randomly among phospholipids
• 2 main types
• Peripheral / Extrinsic proteins
• Loosely attached at charged surface / hydrophilic part of phospholipid bilayer
• Integral / Intrinsic proteins
• Either partially penetrating the phospholipid bilayer or span the membrane entirely
• Proteins partially embedded in phospholipid bilayer:
• Contains both hydrophilic and hydrophobic regions to interact with charged heads and hydrocarbon tails of phospholipid bilayer respectively
2. Glycoproteins (Also a type of protein but slightly different)
• Interspersed among phospholipids
• Consists of carbohydrate chains bound to peripheral proteins and hydrophilic regions of integral proteins that occur on surface of outer membrane
• Carbohydrate chains involved in recognition of same cell type or adhesion of cells to neighboring cells for immune response
3. Glycolipids
• Interspersed among phospholipids
• Consists of carbohydrate chains bound to polar head of phospholipid (Might not necessarily be phospholipid, most of them is just lipid without the phosphate)
• Involved in recognition of same cell type or cell signaling pathways

Extra:

Question: Why do you not feel pain?

Answer: You will feel pain from your nerve cells, so as long as you do not touch your nerve cells, it will be okay. (An area you hardly feel pain: Elbow:))

Question: Why does seafood have a lot of cholesterol?

Answer: This is because of the cold temperature. Cholesterol helps you adapt to a cold environment, and prevents the membrane from becoming frozen.